Joint darkening may be caused by genetic factors, pigmentation, trauma, skin inflammation, acanthosis nigricans, and other reasons. It is necessary to improve it through daily care, medication, and laser treatment. Here are the specific reasons:

1. Genetic Factors

If both parents or one of them has dark joints, it may lead to the same condition in their children. No special adjustment is needed when there are no clinical symptoms.

2. Pigmentation

It is mainly caused by frequent friction, which can lead to melanin deposition and darkened skin color. This can be improved by reducing friction.

3. Trauma

It is caused by external impact or bumps, which may induce local hematoma and darkened skin color. It can be improved through cold or hot compresses.

4. Skin Inflammation

It is mainly caused by inflammation in the skin of the finger joints. After being stimulated by inflammation, there may be an increase in melanin. It is necessary to use erythromycin ointment, mupirocin ointment, fusidic acid cream, and other drugs under the guidance of a doctor for adjustment.

5. Acanthosis Nigricans

It may cause skin pigmentation and darkened skin color, affecting the local appearance. Laser treatment can be used to achieve the removal effect. During the treatment, diet should be adjusted, with a focus on light and easy-to-digest foods. Sun protection measures should also be taken when going out.